JPH0498736A - Manufacture of helix type travelling wave tube - Google Patents

Abstract

PURPOSE:To obtain a travelling wave tube having a cyclic magnetic field device in which it is easy to control for making an electron beam pass in a slow wave circuit by high frequency brazing troidal magnetic pole pieces to a vacuum outer vessel forming the slow wave circuit in a reducing atmosphere. CONSTITUTION:Three dielectric support bars 2 are arranged at equal intervals on the periphery of a helical slow wave circuit 1 of W or the like, and being transformed by applying an external pressure from the outside of a cylindrical metal outer vessel 3 and being inserted in a state that the helical slow circuit 1 and the dielectric support bars 2 are combined into a bore and the external pressure is removed, and being supported and fixed by a restoring force. The troidal magnetic pole pieces 4 are accurately fitted on the periphery of the outer vessel 3 and the outer vessel 3 and the troidal magnet pole pieces 4 are brazed by brazing material 5 being melted by a high frequency brazing device in a reducing atmosphere, by using a high accuracy jig so as to take spaces according to the thickness of magnets. The brazing material 5 is such comparatively low melting point brazing material as having a slightly higher melting point than the temperature of the evacuating process of a travelling wave tube. The heat being generated in the slow wave circuit is effectively transferred to the outside and the passing through of the electron beam becomes easy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing a helical traveling wave tube, and more particularly to a method for manufacturing a helical-socket traveling wave tube having a periodic magnetic field device for focusing an electron beam. .

[Conventional technology]

As is well known, a helical traveling wave tube (hereinafter referred to as a traveling wave tube) has the function of amplifying high frequencies through the interaction of the high frequency waves propagating on a slow wave circuit and an electron beam. It consists of a gun, a slow-wave circuit that amplifies the high-frequency waves by combining the electron beam with the high-frequency waves, a collector electrode that captures the electron beam, and a focusing magnetic circuit that prevents the electron beam from dispersing within the slow-wave circuit. There is.

In traveling wave tubes, in order to pass the electron beam close to the slow wave circuit, a part of the electron beam collides with the slow wave circuit and generates heat, or the electron beam propagates on the slow wave circuit. The heat generated by the slow-wave circuit is caused by heat generation due to loss of high-frequency power, but the heat generation effect of such a slow-wave circuit causes the temperature of the slow-wave circuit to rise in a slow-wave circuit with a small heat capacity, resulting in an increase in high-frequency loss and slow wave generation. The amount of gas released from the circuit increases, which not only causes problems such as decreased output and increased noise, but also shortens its life.

As mentioned above, in order to suppress the heat generated when the electronic beam collides with the slow-wave circuit, it is necessary to improve the accuracy of parts to accurately hold the center axis on the shaft, as well as to optimize the design of the magnetic circuit, etc. It is important to avoid collisions with the electron beam or slow wave circuit. Furthermore, in order to deal with heat generated due to loss of high-frequency power, it is necessary to efficiently dissipate the generated heat to the outside.

In a slow wave circuit placed in a high vacuum, it is thought that most of the heat is dissipated by thermal conduction, so each component forming the slow wave circuit structure is designed to have high thermal conductivity and good contact between the components. The thermal resistance must be kept sufficiently low to improve the heat dissipation effect.

Here, to explain the structure of a general slow-wave circuit structure, the structure of a slow-wave circuit structure using a cylindrical metal envelope is such that the cylindrical metal envelope is deformed by applying pressure from the outside. A plurality of dielectric support rods are arranged around the outer periphery of the spiral slow wave circuit, and the combined state is inserted into a cylindrical metal envelope, and then an external pressure is applied to the cylindrical metal envelope. -2 A method is used in which the slow wave circuit and the dielectric support rod are firmly fastened and fixed using the metal elastic restoring force of the cylindrical metal envelope.

Therefore, the heat generated in the slow wave circuit is efficiently transferred to the cylindrical metal envelope via the dielectric support rod. The heat of the slow wave circuit is usually transferred to a magnetic circuit component fitted into a cylindrical metal envelope and cooled by conduction to the outside from the magnetic circuit component, or is radiated by forced air cooling.

An example of the structure of a conventional slow wave circuit and periodic magnetic field device will be explained with reference to FIGS. 3(a) and 3(b).

In FIGS. 3(a) and 3(b), three dielectric support rods 2 are arranged at equal intervals around the outer periphery of a helical slow wave circuit 1 made of a high melting point material such as molybdenum or tungsten, and are shaped like a cylinder. The metal envelope 3 is deformed by applying pressure from the outside, and the combination of the helical slow wave circuit 1 and the dielectric support rod 2 is inserted into the inner diameter part of the cylindrical metal envelope 3, and then the cylindrical The external force of the cylindrical metal envelope 3 is removed, and the helical slow wave circuit 1 and the dielectric support rod 2 are connected by the metal elastic restoring force of the cylindrical metal envelope 3.
Firmly support and fix.

Further, an annular magnetic pole piece 4 having an axially extending portion 4a is fitted into the outer circumference of the cylindrical metal envelope 3, and an annular magneto-soto 6 divided into two is fitted into the annular magnetic pole piece 4. The built-in annular magnetic pole piece 4 and the two-part annular magnet 6 are arranged alternately,
It constitutes a periodic magnetic field device.

[Invention or problem to be solved]

As described above, in the structure of the conventional periodic magnetic field device, the cylindrical metal envelope 3 and the annular magnetic pole piece 4 must fit smoothly, so a certain amount of clearance is provided. Therefore, the mechanical contact between the cylindrical metal envelope 3 and the annular magnetic pole piece 4 is poor, and therefore, in order to improve heat dissipation, an inclusion 7 that improves heat conduction must be placed on the contact surface. There were some drawbacks that shouldn't have happened.

Also, as mentioned above, taking a certain amount of leeway is
The center axes of the slow-wave circuit and the magnetic circuit are slightly misaligned, which has a drawback in that it subtly affects the adjustment of passing the electron beam through the slow-wave circuit, making adjustment difficult.

An object of the present invention is to provide a method for manufacturing a traveling wave tube having a periodic magnetic field device that allows easy adjustment of passing an electron beam through a slow wave circuit without the need for placing an inclusion to improve heat dissipation. There is a particular thing.

[Means to solve the problem]

The present invention has an electron gun that generates an electron beam in a vacuum envelope, a slow wave circuit that amplifies high frequencies, and a collector electrode that captures the electron beam, and has an annular shape for focusing the electron beam on the outer periphery. In a method for manufacturing a helical traveling wave tube equipped with a periodic magnetic field device consisting of a magnetic pole piece and an annular magnet, the annular magnetic pole piece is applied to the vacuum envelope forming the slow wave circuit in a reducing atmosphere using a high-frequency wax. It is configured to include the steps of attaching.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIGS. 1(a) and 1(b) are a sectional view illustrating a first embodiment of the present invention and a sectional view of an annular magnetic pole piece.

The first embodiment, as shown in FIGS. 1(a) and (b),
The slow wave circuit structure has three dielectric support rods 2 arranged at equal intervals around the outer periphery of a helical slow wave circuit 1 made of a high melting point material such as molybdenum or tungsten, and a cylindrical metal envelope 3. A spiral slow wave circuit l and a dielectric support rod 2 are attached to the inner diameter of the cylindrical metal envelope 3 by applying external pressure from the outside to deform it.
are inserted in the combined state, and then the cylindrical metal envelope 3 is inserted.
The external pressure is removed, and the helical slow wave circuit 1 and the dielectric support rod 2 are firmly supported and fixed by the metal elastic restoring force of the cylindrical metal envelope 3.

An annular magnetic pole piece 4 is fitted onto the outer periphery of the cylindrical metal envelope 3 with high precision, and the cylindrical metal envelope 3 and the annular magnetic pole piece 4
In this method, a high-precision jig is used so that the spacing matches the thickness of the magnet, and brazing is performed by melting the brazing material 5 using a high-frequency brazing device in a reducing atmosphere. The brazing filler metal 5 used here is a relatively low-melting-point brazing filler metal that has a melting point slightly higher than the temperature in the exhaust process of the traveling wave tube.

In this way, the cylindrical metal envelope 3 and the annular magnetic pole piece 4 are brazed with the brazing material 5, and the annular magnet 6 divided into two parts is inserted between the annular magnetic pole piece 4, alternating the polarity of the magnet. It constitutes a magnetic field device.

In such a structure in which the spiral slow-wave circuit and the dielectric support rod are supported and fixed by the metal elastic restoring force of the vacuum envelope, the annular magnetic pole piece fitted into the vacuum envelope is brazed. When brazing the entire body at a raised temperature, the metal may soften due to annealing, which weakens the metal's elastic restoring force, which is undesirable.

In the case of high-frequency brazing as in this example, it is possible to braze the parts by heating for a short time, and there is little change in the performance of the metal. A joining method using high-frequency brazing equipment is suitable.

FIGS. 2(a) and 2(b) are a sectional view illustrating a second embodiment of the present invention and a sectional view of an annular magnetic pole piece.

The method of configuring the slow wave circuit structure is the same as in the first embodiment.

The second embodiment, as shown in FIGS. 2(a) and (b),
The magnetic pole is a tapered annular magnetic pole piece 8 which has a tapered part on the inner diameter part and a fitting allowance on a part of the inner diameter part so that the slow wave circuit part and the periodic magnetic field device force center axis can be more easily aligned. is arranged, and a two-divided tapered magnetic pole piece 9 is arranged inside it. After accurately dimensioning the central axes of the slow wave circuit section and the magnetic circuit section in this way, using a high frequency brazing device,
The cylindrical metal envelope 3 of the slow-wave circuit portion and the tapered annular magnetic pole piece 8 and the two-part tapered magnetic pole piece 9 are brazed with a brazing material 5.

When these magnetic pole structures are used, it is possible to construct a highly accurate magnetic circuit suitable for relatively large magnetic poles.

〔Effect of the invention〕

As explained above, according to the present invention, the cylindrical metal envelope of the slow wave circuit structure and the periodic magnetic field device are mechanically joined, so that the cylindrical metal envelope that was implemented in the conventional structure is There is no need to place an inclusion in the fitting part with the annular magnetic pole piece to improve heat conduction, and there is also a movable space between the cylindrical metal envelope and the annular magnetic pole piece. By providing a certain degree of clearance, the adverse effects caused by slight misalignment of the central axes between the slow wave circuit structure and the periodic magnetic field device can be eliminated.

Therefore, by brazing the annular magnetic pole piece of the periodic magnetic field device to the cylindrical metal envelope of the slow wave circuit structure, the metals are combined, and the heat generated in the slow wave circuit is efficiently transferred to the outside. In addition, the negative effects caused by slight misalignment of the central axes between the slow wave circuit structure and the periodic magnetic field device when adjusting the electron beam to pass through the slow wave circuit are eliminated.
It is possible to provide a high-performance and inexpensive traveling wave tube through which electron beams can pass easily, and it is particularly suitable for high-output traveling wave tubes of several hundred watts or more.

[Brief explanation of drawings]

FIGS. 1(a) and (b) are a cross-sectional view explaining the first embodiment of the present invention and a cross-sectional view of an annular magnetic pole piece, and FIG. 2(a), fl
:+) is a sectional view explaining the second embodiment of the present invention and a sectional view of an annular magnetic pole piece; FIGS. 1. A helical slow wave circuit, 2. A dielectric support rod, 3. A cylindrical metal envelope, 4. Annular magnetic pole pieces, 4a, 8a... of annular magnetic pole pieces. Extended part, U... Brazing metal,... Two-part annular magnet, 7 - Inclusion, 8 - Tapered annular magnetic pole piece, 9... 2
Split tapered pole piece.

Claims (1)

[Claims] It has an electron gun that generates an electron beam in a vacuum envelope, a slow wave circuit that amplifies high frequencies, and a collector electrode that captures the electron beam, and an annular magnetic pole piece and an annular magnetic pole piece for focusing the electron beam on the outer periphery. A method for manufacturing a helical traveling wave tube equipped with a periodic magnetic field device consisting of a magnet includes the step of high-frequency brazing the annular magnetic pole piece to the vacuum envelope forming the slow wave circuit in a reducing atmosphere. A method for manufacturing a helical traveling wave tube, comprising: